Hibernate: How to use cascade in annotation?

How can I use cascade and annotations in hibernate?

But I stay with a doubt:

I have this situation:

public class Package(){
  @OneToOne(cascade=CascadeType.PERSIST)
  private Product product;

  @OneToOne(cascade=CascadeType.PERSIST)
  private User user;
  ..
}

When I try to session.save(package), an error occurs. I don't want to save product and package. I just want to initialize and set them into my package object.

Is that possible?